A conventional core used in a winding device is forwarded into a curved channel through the conveyance of a conveyor and a push plate in order to be transported to a winding zone in which a thin web material is wound on the core to form a roll, such as a toilet tissue roll and a kitchen towel roll. After the roll is completed, a cutter is employed to cut the thin web material or the rotational speed of a rotary bar is controlled to have a relative speed thereof with respect to a first winding roller or a second winding roller slower so as to induce a speed difference, which breaks or tears off the thin web material.